MLS Study Guide 2026
Everything you need to pass the MLS exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 MLS Exam Format at a Glance
📚 MLS Topics to Study (63)
✍️ Sample MLS Questions & Answers
1. Which of the following is a critical component of a laboratory’s quality assurance (QA) program?
Proficiency testing is a key part of quality assurance, helping to evaluate a laboratory’s ability to produce accurate and consistent test results.
2. Which anticoagulant is used in the light blue (sodium citrate) tube and what is its primary application?
Sodium citrate chelates calcium to prevent clotting and is the required anticoagulant for PT, aPTT, and other coagulation assays.
3. A pediatric patient with acute lymphoblastic leukemia (ALL) on maintenance therapy has an ANC of 450/µL. Per standard protocol management, the MOST appropriate action is:
ALL maintenance protocols hold antimetabolites (MTX and 6-MP) when ANC falls below 500–750/µL to prevent life-threatening neutropenia, with CBC recheck to guide restart.
4. A urine culture grows >100,000 CFU/mL of a lactose-fermenting gram-negative rod. Oxidase is negative. Most likely organism is:
E. coli is oxidase-negative, lactose-fermenting, and is the most common cause of community-acquired urinary tract infections at significant colony counts.
5. Which action is required when a pipette calibration check shows a systematic error of 3% at all volume settings?
A systematic 3% error at all volumes exceeds most laboratory tolerance limits and requires the pipette to be removed from service for recalibration or repair.
6. During a flooding emergency in the laboratory basement where specimens are processed, the FIRST priority for the MLS on duty is:
Personal safety and evacuation of personnel is always the first priority in any emergency before addressing equipment, specimens, or data.